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Fri, 22 Jan 2021 22:30:22 +0000 (GMT) References: <20210121173003.18324-1-nramas@linux.microsoft.com> User-agent: mu4e 1.4.10; emacs 27.1 From: Thiago Jung Bauermann To: Lakshmi Ramasubramanian Subject: Re: [PATCH 1/2] ima: Free IMA measurement buffer on error In-reply-to: <20210121173003.18324-1-nramas@linux.microsoft.com> Date: Fri, 22 Jan 2021 19:30:20 -0300 Message-ID: <87eeic1u6b.fsf@manicouagan.localdomain> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343, 18.0.737 definitions=2021-01-22_15:2021-01-22, 2021-01-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 clxscore=1011 phishscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 suspectscore=0 bulkscore=0 mlxlogscore=999 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101220112 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sashal@kernel.org, dmitry.kasatkin@gmail.com, linux-kernel@vger.kernel.org, zohar@linux.ibm.com, tyhicks@linux.microsoft.com, ebiederm@xmission.com, gregkh@linuxfoundation.org, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Lakshmi, Lakshmi Ramasubramanian writes: > IMA allocates kernel virtual memory to carry forward the measurement > list, from the current kernel to the next kernel on kexec system call, > in ima_add_kexec_buffer() function. In error code paths this memory > is not freed resulting in memory leak. > > Free the memory allocated for the IMA measurement list in > the error code paths in ima_add_kexec_buffer() function. > > Signed-off-by: Lakshmi Ramasubramanian > Suggested-by: Tyler Hicks > Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list") > --- > security/integrity/ima/ima_kexec.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index 121de3e04af2..212145008a01 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image) > ret = kexec_add_buffer(&kbuf); > if (ret) { > pr_err("Error passing over kexec measurement buffer.\n"); > + vfree(kexec_buffer); > return; > } This is a good catch. > > ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size); > if (ret) { > pr_err("Error passing over kexec measurement buffer.\n"); > + vfree(kexec_buffer); > return; > } But this would cause problems, because the buffer is still there in the kimage and would cause kimage_load_segment() to access invalid memory. There's no function to undo a kexec_add_buffer() to avoid this problem, so I'd suggest just accepting the leak in this case. Fortunately, the current implementations of arch_ima_add_kexec_buffer() are very simple and cannot fail, so this is a theoretical problem. -- Thiago Jung Bauermann IBM Linux Technology Center